<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="../react18/react.development.js"></script>
  <script src="../react18/react-dom.development.js"></script>
  <script src="../react18/babel.min.js"></script>
</head>

<body>
  <div id="app"></div>
  <script type="text/babel">

    class Parent extends React.Component{
      state={
        car:"奥拓"
      }

      render(){
        const {car}=this.state;
        return (
          <div>
          <h1>我是父类组件</h1>
          <p>我用的车是{car}</p>
          <button onClick={this.changeCarHandle}>换个车</button>

          <Child a={1}  car={car}/>
          </div>
        )
        
      }

      changeCarHandle=()=>{
        this.setState({car:"奥迪"})
      }
    }

    class Child extends React.Component{
     
      /* 
        当父组件更新状态的时候,子组件的render方法会重新执行生成新的虚拟DOM,也能拿到最新的props
      */
      render(){
        console.log("Child组件实例",this)
        // props是组件实例上的属性
        const {car}=this.props;
        return (
          <div>
          <h1>我是子类组件</h1>
          <p>我用的车是{car}</p>
          </div>
        )
        
      }
    }

    const root = ReactDOM.createRoot(document.getElementById('app'));
    root.render(<Parent/>)


  </script>
</body>

</html>